A similar setup.
I suppose that is what is good about a two wire led inside a small tube. The light can only be thrown in one obvious direction creating a circle of light and does not need to be blinding bright.
My tube is a drilled out threaded rod given to me by another ATM and can be threaded in to a plate or bolted on.
Quote:
Originally Posted by mura_gadi
Hello,
I have just made my Ronchi tester, but not the stand. I used a LED from a cheap $10 headlamp from Jaycar, the printed Stellafane pdf transparency and fixed it inside a 35mm slide. Worked really well, unbelievable the detail on the blanks surface...
The one thing I found tricky was the alignment, I used a A3 sheet behind the tester to locate the returning beam. Once you have the returning beam it is a lot easier to locate your RoC and to align the tester/blank so the returning beam lands on the correct part of the transparency/Ronchi bands.
What ever the design just make sure you can get your eye in really close to the screen. That is probably the single most important thing to get right.
Steve
Ps. My LED is really bright, I was thinking of using a milk bottle cutout as a diffuser. The board is about 8mm thick, and the bulb is inset to about 3mm away from the screen. I was having trouble with light leaks, the insert was the easiest way for me to cancel them and it got the light source close to the screen.
I found that if you move the stand forward after getting the bands right, you can lose the bands and get a Foucault like test image from the blank as well.
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